Passive Control of Cylinder Wake by a Downstream Splitter Plate Placed Behind Critical Gap Ratio

Computations of flow past a square cylinder with a thin flat splitter plate kept beyond critical gap ratio, (G/a)C ≈ 2.3, are investigated using Ansys Fluent. A total 16 cases have been computed considering the plates position varying in between G/a = 2.5 − 4 and y/a = 0 − 0.75. Here, the gap between cylinder and plate is denoted by ‘G’, whereas the side of the square cylinder is represented by ‘a’. The splitter plate length is also kept as ‘a’. The vertical distance between the centrelines of the cylinder and the splitter plate is denoted by ‘y’. The Reynold’s number Re is considered 100 based on ‘a’ and inlet free stream velocity U∞. SIMPLE algorithm is used to solve the unsteady two-dimensional, incompressible momentum (Navier–Stokes) equations, where the least squares cell-based method is used to evaluate the gradients. Instantaneous and mean flow visualizations are depicted to understand the flow physics due to interaction between the wake from square cylinder and the boundary layer of splitter plate. It has been observed that beyond (G/a)C, as the plate is moved further from the square cylinder both in horizontal and vertical directions, the shear layers of the cylinder roll-up properly and these vortices interact with the splitter plate boundary layer, which eventually changes the flow dynamics far downstream.